In a flash memory, error management units which store information on a physical occurrence position of an error which occurred during data reading are prepared by as much as the number of bits which can be corrected by an error correction code, in a redundant portion of a physical page. Differentiated error detection is achieved in that a second temperature model band is calculated for the case in which the thermostat remains in the opened state. The modulator re-modulates the amplitude of the optical signal in a continues fashion with a waveform that is periodic, whose fundamental frequency is equal to the same predetermined frequency at which the data is modulated onto the optical signal. The second communication devices may each include a low voltage power line port configured to communicate with a plurality of user devices via a low voltage power line and a second port for communicating with the first communication device. Therefore, a substrate mounted on a substrate table integrated with the mover is precisely positioned. It also allows parasitic interactions on top of the IPD substrate to be reduced by selective placement of IC semiconductor chips and IC chip ground planes.